Vertical injection press



Nov. 2, 1943. w. R. TUCKER 2,333,601

# VERTICAL INJECTION PRESS Filed April 22, 1940 3 Sheets-Sheet I151.

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VERTICAL mmcnon- PRESS Filed-April 22, 1940 a Sheets-Sheet 6 .IEll.

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vEn'rIc-AL mmc'noN riuiss Warren It. Tucker, Dayton, Ohio, asslgnor to The Hydraulic Development Corp. Inc., Wil- "mington, Del., aoorporation Delaware Application. April 22, 1940. Serial No.- asoscs 16 Claims.

This invention relates to an injection molding press and more particularly to a vertical injection press. A K

It is an object or the present invention to provide a vertical imection molding press which is more compact, than injection molding presses heretofore devised and which occupies much less iicor space than horizontal presses and much less head room than vertical presses heretofore available.

Another object is to still further decrease the 8 head room required for the press by placing the main cylinders in the base of the press.

- Another'object is to provide for more effectiv clamping and injection and for more effective re-. turn of the injection plunger after the injection stroke.

Still another object is to provide a press of simpliiled construction and having simplified controls.

Another object is to provide an injection molding press having a fully automatic complete cycle of operation whereby it is unnecessary to manually manipulate the various parts of the press.

Still another object is to utilize advantageously hydraulic motors which are oppositely arranged and which have differential areas in such manner as to obtain improved and more flexible control of the press.

Another object is to obtain higher speeds of the moving parts of the press, for example to obtain a faster traverse preparatory. to the injection stroke, a more rapid injection stroke than has been heretofore possible, and a more rapid return stroke.

Another object is to attain these advantages of higher speeds without using an accumulator which vantageous result.

Another object is to provide for automaticdwell of the press at-the end of the injection stroke, and after a portion of the return stroke,

but before unclamping oi the mold.

Another object is to provide feeding mechanism which accurately gauges the amount or plastic fed to the injection cylinder in direct proportion to the requirements of the injection cylinder whereby the injection plunger always stops at' approximately the same position. apreferred torm, means is provided which is readily accessible to the operator adjacent the floor for adjusting the rate of feed and for changing the position at which the injection plunger stops in its stroke.

Still other objects will more fully hereinafter appear.

In the accompanying drawings:

Fig. 1 is a front elevation of a press embodying the principles of the present invention.

Fig. 2 is a vertical section taken on the linethe direction of the 2-2 of Fig. 3, looking in arrows.

Fig. 3 is a right-hand side elevation of the press. Fig. 41s a detailed section on the line -dd of Fig. 5, looking in the direction of the arrows. This view shows in detail one of the main cylinders.

Fig. 5 is a horizontal-section taken on the line 5-5 of Fig. 1, looking in the direction of the ar- 7 rows.

Fig. 6 is a horizontal section on the line t-6 of Fig. 2, looking in the direction of the arrows.

Fig. 7 is a horizontal section on the line 'll of Fig. 2, looking in the direction of the arrows.

Fig. 8 is a vertical section on the line t-8 of Fig. 3. This view shows details of the automatically proportioning feeding mechanism.

Fig. 9 is a vertical section on the line 9-9 of v Fig. 8 showing details of the one-way feeding sprocket.

Fig. .10 is a vertical section on the line lit-l0 of Fig. 2, looking in the directionof the arrows, and shows in detail the feed chamber surrounding the injection plunger.

Fig. 11 is a diagrammatic view showing the press arrangement and showing the hydraulic and electrical circuits-01 the control thereof.

- Figs. 12 to 15 portray a modified form of the invention in which the main ram is carried in the stationary head of the press and in which the push-back and the main ram are combined in a single double-acting differential hydraulic motor.

In these views;

Fig. 12 is a front elevation of the modified form of the press.

Fig. 13 is a partial vertical sectionof the press I of Fig. 12.

Fig. 14 is adiagrammatic view of this modified form of press and is similar to the diagrammatic view comprised in Fig. 11.

Fig. 15 is a horizontal section on the line I-I5 of Fig. 13, looking in the direction of the arrows and shows details of the heating chamber arrangement.

Referring to the accompanying drawings in detail and first particularly to the form shown in Figs, 1 to 11, I designates the bed of the press upon which is fixedly mounted or held by gravity the lower bolster 2 carrying the lower mold half 3. The upper mold half 4 is carried by the upper bolster 5 which is 'operatively connected to the clamping and cushioning pistons 6 by clamping rods 1 which are attached in any suitable manner at their lower ends to the upper bolster 5.

The pistons 6 are adapted to reciprocate within the clamping and cushioning cylinders 8 which are formed integrally with the clamping and injecting head 9 of the press, these cylinders 8 being formed within this clamping and injecting head 9 which is in the form of a hollow casting.

Depending from and fixedly attached at their upper ends in any suitable manner to the head 9 are a pair of rods Illa and lb which function as both booster and push-back rods, having mounted fixedly at;their lower ends the booster and push-back pistons Ila and I"). These pistons Ila and II?) reciprocate within cylinders I2 formed in the bed I, as for example by being made integral with the casting which constitutes the bed I. The space above pistons Na and Nb is employed for pulling the head 9 downwardly while the space below these pistons is employed to push the head 9 upwardly.

The rods Ida and lb have mounted on them in any suitable manner collars I3 which support the injection cylinder carrying platen I 4 so that platen I4 is free to traverse that portion of rods Ilia and IIlb which lies between the collars I3 and the head 9. Platen I4 is supported by gravity on the collars I3 when the press is in the position shown in the drawings. Platen I 4 is made up of an upper plate I5 and a lower plate I6, these plates being secured together in spaced relationship by the webs ll of plate I5 and suitable bolts passing through plate I6 into the webs II.

Fixedly mounted on platen I4 is the injection cylinder designated generally as I8, this injection cylinder being attached to the upper plate I5 centrally thereof by means of the hopper I9 which forms the upper portion of the injection cylinder and which constitutes a feed chamber for holding a reserve of granular plastic in a manner which will presently appear. The injec-- tion cylinder I8 depends therefrom downwardly through the plate I5 which when the press is retracted is held a short distance above the upper bolster 5. The injection cylinder I8 is thus held initially a somewhat smaller distance from the bolster 5 so that when the platen I l is lowered, the injection nozzle 20 will engage the injection gate 2I of the mold half 4 before the plate I5 rests upon the upper bolster 5. V

Contained within the platen I4 are a pair of heating means makes for a more compact and neater assembly. I

Secured to and depending downwardly from head 9 in a manner similar to rods Ila and Ill) vided with main pistons 26a and 26b which operate slidably within the vertical cylinders 21 formed integrally with the casting of the bed I. The space above these pistons is employed as the main pressing area in a. manner which will presently appear. The space below these pistons is in constant and free communication with a lower liquid tank 28 formed in the bed I of the press by the casting thereof. This communication is maintained by the ports 29 (Fig. 4) formed at the bottom of cylinders 21 on the side thereof adjacent the reservoir 28. -The space above these pistons is in constant check-valved communication with the reservoir 2'8 by the conduits 30 which extend through the walls of cylinders 21 into the tank 28 and which are provided on their inward ends with check valve 3I which allow liquid to freely flow from the tank into these spaces but prevent the reverse flow.

The main rods 25a are provided with bores 32 (Fig. 11) which extend from their uppermost end down through the pistons 260 into communication with the spaces below pistons 26a. These bores 32 are also in free and constant communication with :an oil reservoir 33 formed in the .a line 35 to a line 35 leading to the spaces above clamping pistons 6. A check valve 31 is disposed in this line 35 in such manner as to allow the free flow upwardly therein but to prevent the reverse flow. The other bore 34 is provided at its upper end with a pipe 38 which connects to the line 35 above the check valve 31. Pipe 38 is provided with a check valve 39 which allows liquid to freely flow downwardly but prevents the upward flow. Interposed in line 38 is a relief or unloading valve 80 which is adapted to be actuated by the pressure built up in line 35 transmitted through a line 4| from line 35 to actuate the'valve 40 so as to allow free discharge from the space above clamping pistons 6 when the pressure thereabove exceeds a predetermined amount. The valve 40 is preferably made adjustable so as to allow. for adjustment of the pressure at which unloading will take place and thus adjustment of the clamping pressure. As will be obvious, valve 40 is normally closed and is opened only after the mold halves are clamped under a predetermined pressure and allows the clamping and injecting head 9 to travel downwardly, causing the pistons 6 to be'telescoped in the clamping cylinders 8.

tons 6, the ports 42 are provided in the lower portions of clamping cylinders 8, these ports leadheating tanks 22 "from which heated oil or the,

ing directly into the upper reservoir 33.

The clamping and injecting head 9 carries on its lower face the injection plunger 43 which is slidably received downwardly through a bore in the upper plate I5 of the injection cylinder carrying platen I4 and which is in alignment with the injection cylinder I8.

The right-hand booster and push-back rod Illa is provided with an axial bore 44 which communicates at its lower end with the space above booster and push-back piston Ila and which communicates at its top with the line 30 which is provided with a check valve 43 which allows liquid Pressureirorn above the booster and U -back piston lid to be transmitted to the clamping cylinders 3 but prevents the reverse flow of liquid. The left-hand booster and push-back rod Jill: is provided with an axial bore 43 which'extends downwardly through the booster and push-back piston ilb into communication with the space therebelow and which at its upper. end is connected to the other end of line 36 which is provided with a check valve 41 which is adapted to allowliquid pressure from below piston lib to be transmitted to the clamping cylinders 8 but to prevent 'the reverse flow of. liquid. Thus, since one or more of the main pressing areas, the booster area and the push-back area is supplied with liquid prmsure at all times, the clamping pistons are at all times supplied with liquid pressure.

Feeding mechanism The feeding mechanism is portrayed in Figs. 1 to 3 and 8 to 10 and comprises a hopper 48 for granular material'mounted on a right-hand extension of the upper plate of the platen N. This hopper 48 is adapted to feed granular material into the cylindrical bore 49 formed in the plate IS. A screw conveyor 50 is disposed in the bore t9 and is adapted to feed the material inwardly through a .downwardly extending bore 5i into the feed chamber it which is disposed above and around the injection bore of the injection cylinder l8. Mounted on the outward end of the shaft 52 of the screw-conveyor 50 is a drive pinion 53. Pinion 53 is adapted to drive shaft 52 in only one direction of rotation through the intermediary of the rollers 5d which are disposed in the tapering slots 55. The silent ratchet thus formed is adaptedto drive feed screw 50 only when the pinion 53 is rotated in the direction indicated by the arrow in Fig. 9. Pinion 53 is adapted to idle when it is rotated in the reverse direction.

Adapted to drive feed pinion 53 is a rack 56 which is screw-threadedly mounted on an actuating and adjusting rod 5'! mounted vertically on the right-hand side of the press. Rod 51 has at its upper end a fixedly attached collar 53 which is received rotatably between the ears 59 which are fixedly carried on the head 9 and which prevent rod 57 from moving vertically relative to head 9 but allow free rotation thereof. the rack 56 may be adjusted vertically by rotating rod 51 by means of the hand wheel til at 'its lower end which is readily accessible to the operator. In order to adjust the point of stopping of the injection plunger 83, the rack 55 is adjusted vertically by means of the hand wheel St. The adjustment is efiective by changing the point at Thus' which the lower end SI of the rack 56 engages the pinion 53 and starts rotation thereof on the downward stroke of head Q. Thus, if rack 55 is moved upwardly, itsend 8i will not engage the pinion 53 until later and consequently feed screw 50 will be rotated a less amount as th head 3 moves downward in its injection stroke. It will be understood that while the arrangement is shown as-"feeding during the down-stroke of head 3, if desired it may be reversed so that feeding takes place during the upstroke.

From the foregoing, it will be seen that no feeding takes place while the head 9 and the platen 14 are moving downwardly together bewhich injection plunger 43 is received within the injection cylinder Hi. .It will be understood that when the injection plunger 43 i retracted from the injection cylinder IS, the material which was fed into and which accumulated in chamber is around injection plunger 43 on the-down-stroke will fall downwardly by gravity into the upper portion or the injection cylinder l8 so as to replace the material which was injected into the mold.

' It will further be seen that by adjustment of thehand wheel and consequent adjustment of the point of engagement of the rack 56 with the pinion 53, the point at which the injection plunger 43 comes to rest may be adjusted to suit the parsize of the molded piece, it will be seen that by the feeding arrangement herein provided, conditions may be readily adjusted so as to bring about this desirable result with a piece of any size. 1

Hydraulic and electrical circuits The hydraulic and electrical circuits are portrayed in Fig. .11. The liquid pressure for actuating the various hydraulic motors is supplied by means of a one-way variable delivery pump a: which draws liquid from the tank 28 through the conduit 63 and supplies it under pressure to the conduit M which leads to inlet ports of control valves 65 and 66, valve 65 being a three-way valve and valve 66 being a four-way valve.

The electrical connections are as follows:

Valve 65 is provided with a solenoid fii-which when energized is adapted to pull the valve member thereof from the normal position shown in Fig. 11 downwardly against the action of spring 68, thereby shifting valve 55. The valve member of valve 56 is adapted to normally lie downwardly in the position shown in Fig. 11 and to be moved upwardly by the solenoid 69. Solenoid 69 is connected in parallel with a solenoid it which is adapted when energized to pull its armature ll upwardly, thereby making two circuits which will be described presently. One side of the solenoids S9 and it is connected by a line 12 to the power line 73 which is prowided with emergency switch id for discontinuing the application of power to the press. The other power line is designated as it. The other side of solenoid 69 and id is connected by a line lt'to one side of a normally open limit switch TI which is adapted to be actuated by a cam '18 adjustably carried on a rod 19 which is mounted on the head ii.

armature 82 of a. solenoid 81 which is connected in parallel with solenoid 8-1. The corresponding lower contact is connected by a line 83 to the power line 14.

The upper contacts adapted to be connected by the armature 82 are connected as follows: One of them is connected by a line 84 to the power line I3. The corresponding upper contact is connected to a line 85 which is connected to one side of solenoids 61 and 8| and which is also connected toone side of a switch 86. The other side of solenoids 61 and 8| is connected by a line 81 through a normally closed time switch 88 to the power line I4. Switch 88 is adapted to be opened by a timer motor 89. The other side of the switch 86 is connected by a line 90 to the line 84 and thus to the power line I3. Interposed in the line 90 is a repeat limit switch 9|. For automatic operation, the switch 86 is locked up against the upper contacts andthe limit switch 9I which is closed only when the press head 9 isv up and which is otherwise open, is adapted to be closed by the press head 9 reaching the limit of its upward travel, thereby causing press head 9 to execute another injection stroke. For manual operation, the switch 86 is pushed down for an instant against the lower pair of contacts and is then released.

'Another timer motor 92 is provided which is adapted to open a normally closed time switch 93, one side of which is connected by a line 94 to the power line I4 and th other side of which is connected by a line 95 to an upper contact adapted to be connected by the upper switch blade carried by armature 'II to the point of juncture 96 of line I6 with the lower. ends of the coils of solenoids 69 and ID. The timer motors 89 and 92 are connected in parallel, one

side being connected by a line 91 to the power line I4 and the other side being connected by a line 98 to a contact adapted to be engaged by the lower switch blade carried by armature H, the corresponding contact of which is connected to the line I2 leading to the power line I3.

The hydraulic connections are as follows:

A conduit 99 leads from the outlet conduit 64 of pump 62 to a. servomotor I06 mounted operatively on the pump 62 whereby the pump is shifted towards neutral when a predetermined pressure is developed in conduit 64. This enables the holding of the injection plunger 43 inwardly under pressure at the end of the injection stroke.

The main pressing areas located above the main pistons 26a and 26b are connected to the branched conduit IDI which leads by the conduit I02 to the upper service port of valve 66. The booster areas above pistons lid and III) are connected to the conduit I03 which is con nected by the conduit I04 to the other service port of valve 66. The push-back areas below stons Ila. and Ilb are connected by conduits I05 to a conduit I06 to the service port of the other valve 65. The return port of valve 65 is connected bv a return conduit I0'I back to the tank 28. The upper return port of valve 66 is connected by a conduit I08 to this return condu t I 01. The lower return port of valve 66 is connected by a conduit I09 to the return conduit I01. When valves 65 and 66 are in the position shown in the drawings, valve 65 supplies l qu d pressure into the push-back areas below pistons Ila and Nb, while valve 66 supplies liquid pressure into the booster areas above these pistons. Since the push-back areas are greater than the booster areas, this causes the press head 9 to be held in its uppermost position. If the valve member in valve 65 is shifted downwardly, it cuts on the application of pressure to the pushback areas, allowing them to be connected to the tank 28. This causes the push-back pistons Ila and Nb. to move downwardly under the influence of liquid pressure applied to the booster areas thereabove. Should the valve member in valve 66 be shifted upwardly to the limit of its upward travel by energizing of solenoid 69, the main areas above pistons 26a and 28b will be disconnected from the tank 28 and will be supplied with liquid pressure and at the same time the application of liquidpressure to the booster areas will be discontinued and these booster areas will be connected to the tank 28 ,by the return conduit I09.

In order to limit the upward travel of the press head 9, the left-hand push-back cylinder I2 is provided with an over-travel port III! which is adapted to be connected by a two-way valve III to a conduit H2 which connects with the inlet conduit 63 of the pump 62 and thus to the tank 28. The rod I9 carried by the press head 9 is provided with an adjustable collar II3 which is adapted to engage an ear III on a rod H6 at the point where it is desired to have head 8 stopped. The rod H5 is connected integrally to the valve member of valve III. A spring H6 is rovided between the casing valve III and a shoulder III on a downward extension of rod II 5 and is adapted to normally maintain the valve III closed but to yield to allow it to be opened when the head 9 regains its upper position. Thus it is insured that the head 9 will stop its upward movement at a predetermined point and yet the push-back function of the lower side of piston III) is retained. Should the head 9 drift downwardly slightly, it would cause valve I II to be closed, whereupon the pressure delivered into conduit I05 would be immediately applied to the push-back pistons Ho and II b to cause upward travel of head 9 until valve III is opened.

Operation When the press is idling, the parts are as shown in Figs. 1 to 11. The pump 62 is constantly delivering pressure liquid. The valve member of valve 66 is so disposed that the pressure liquid is directed to the booster spaces above pistons Ila and I II). At the same time, the main pressing spaces above pistons 26a and 26b are connected freely to the tank 28 through the upper portion of valve 66. The valve 65 has its member so disposed that the pressure-liquid is simultaneously delivered to the push-back spaces below pistons Ma and IIb. Since the push-back area is greater than the booster area, the head 9 is held up. The rod I9 mounted on head 9 has opened the valve III, allowing the liquid delivered into the push-back spaces to be returned back to the tank 28, thereby holding the head 9 in its uppermost position. The output of the pump 62 is also being constantly delivered to the clamping and cushioning cylinders 8 by reason of the provision of the bore 44 leading to the booster spaces above piston Ila and the bore 45 leading to the spaces below piston MD. This pressure maintains the pistons 6 bottomed in the cylinders 8.

To start head 9 downwardly in a pressing operation, the operator presses the switch 86 downwardly for an instant -or looks it up for fully automatic repeat operation. This energizes solenoids 61 and 8|, the upper repeat limit switch 9I being closed at this time. The energizing of solenoid 8I causes its upper blade to establish a holding circuit for maintaining the solenoids and the holding circuit is established from power p line 12 through line 84 across the upper switch through the solenoids 61 and 8|, through the line 81, through thetimed switch 88 and back to the other power line F4. The energlzingoi solenoid 8| also establishes with its lower blade a connection between lines 89 and 83 such that when limit switch ii is closed at the completion of lamping, it can cause energizing oi solenoids 69 and ill through the line it, through the coils of solenoids t9 and M, and through the line 22 back to the power line it. At the same time, the electrical connection of lines 85 and 83 by the lower switch blade of solenoid 8i prepares the circuit for the energizing of solenoids t9 and i by the closing of limit switch 17 when the clamping has been completed. I

The energization of solenoid 6! in the manner just described causes the valve member of valve 65 to be shifted downwardly so as to cut the application of liquid pressure to the push-back areas below pistons Ha andv lib. The head 8 now moves downwardly at high speed under the action of' liquid pressure applied to the booster areas, the total booster area being small so that fast traverse is obtained. As the head 9 moves downwardly, it carries the mold half d towards the mold half 3, the clamping pistons being supplied with liquid pressure through bore dd oi the rod Wu and projecting the mold half 8 downwardly to the maximum possible extent. After the head 9 reaches a certain point at which the ,ing circuit for holding solenoids 68 and Ed energized, this circuit being from power, line is through line as, through closed timed switch as, through line 95, through the upper switch blade of solenoid it, through solenoids $9 and "iii which are in parallel, to the line l2 back to the other power line it. The energization of solenoid w a circuit' causes its lower blade to establish through timing motors 89 and 92 which are connected in parallel, this circuit being from power line is, through line l2, through the lower switch blade of armature it through line 98, through the motors t9 and 82, and through line 9? to the other power line 95.

The function of the initiation of the t motors 89 and 92 will presently appear. It will be understood that these timing motors are so arranged as to open their switches after a predetermined time which may be variable at the will of theoperator and that these motors are provided with suitable self-contained means for causing their return to the initial position.

The energization of solenoid 69 simultaneously with the energization of solenoid It! causes the valve member in valve 66 to be pulled upwardly. This causes the application of the output of pump 62 into line [Ill and thus to theto'p or the main pistons 26:: and 26b, andsimultaneously causes the discontinuance of the application of pressure liquid to the booster areas so as to obtain a fast areas, the injection would be slower. The head Q continues downwardly under the action of the pressure liquid applied to the main pressing spaces, the application of pressure to the clamping piston 6 being maintained by the bore 34 in the right-hand main rod 25?). As the head 9' continues downward in this manner, the clamping and cushioning pistons 6 remain stationary, clamping having been accomplished to the desired extent. The clamping and injecting head 8 continues beyond the clamping pistons '9, causing discharge of liquid from the clping cylinders 8 through the'reliei or unlong valve dd downwardly through the check. valve 39 and the bore '34 of the left-hand main rod 2% into the spaces above the main pistons 26a and 2%, these spaces all being in communication with one another by means of the conduit idi. This continued movement of the head also causes entry of the injection plunger into the injection cylin- The press maintains the pressing condition until g motor 89 opens the timed switch dd, whereupon solenoids d! and ti are de-ener= gized since the application of power to line 8?? from power line it has been interrupted. The de-energization of solenoid di prepares solemold for the next cycle, e de energization of solenoid or causes the valve member of valve "be which was pulled downwardly to be returned upwardly to its original position shown in Fig. 11

under the influence of spring 68. This causes the output of pump as to beapplied to the line 695 and thus to the push-bach areas below pushback pistons Ma and Nb. This. causes the head 9 to be retracted because the areas otthe cl ing pistons 5 added to the areas of the pushback pistons Ma and lib exceed the main pressing area. Since the pistons t are now telescoped in their cylinders 8, the pressure applied to the push-back spaces is also applied to the clamping cylinders by way of the bore $5 in the rod 5% and is therefore efiective to aid in raising the for the completion of the injection stroke and the holding of the injection plunger 43 under injection pressure so as to allow the article in the mold to be properly formed.

The press continues in the condition iust described-the retraction of the head 9 continuing until the clamping pistons 6 bottom in the head 9. When that happens, retraction of the injection plunger ceases. because when th pistons d bottom, their area is removed from cooperation with the push-back area and the area of the main pressing pistons is greater than the area of the push-back. Any tendency for the main prmsing pistons to force the head 9 down is,

however, instantly counteracted since it unbottoms the clamping pistons 5, rendering their areas eil'ective in conjunction with the push-back area the efiective area of the time to cause upward movement of the head 9 until the pistons 6 bottom. Therefore, the head 9 merely stops in its upward movement and maintains this position because if it moves in either direction from this position, it is instantly returned to it. Meanwhile, the mold halves have remained clamped under the predeterminedpressure and cooling of the molded article is taking lace. p The press maintains this state until the timing motor 92 causes opening of the timed switch 93 after a predetermined time suflicient to allow cooling and hardening of the molded article. The opening of switch 93 causes solenoids 69 and I6 to be de-energized. De-energiziation of solenoid III merely placed it in condition for another cycle. De-energization of solenoid 69 causes the valve Modification of Figures 12 to 15 In Figs. 12 to 15, there is disposed a modified form of the invention in which the clamping and injecting head is moved hydraulically by hydraulic motors located thereabove instead of having the main hydraulic motors, the boosters and the push-backs in the bed of the press. In these views, the bed of the press is designated I20, and is connected to the stationaryhead I2I of the press by the strain rods I22. The lower mold half I23 'is mounted on the bed I while the upper member in valve 66 to fall by gravity to the position shown in Fig. 11, causing the application of liquid pressure to the booster areas by means of conduits I03 and causing the main pressing areas to be freely connected back to the tank 28. This causes the head 9 to begin to rise and to complete its return stroke because the area of push-back exceeds the booster area. By connecting both the booster and the push-back to the same limited source of liquid pressure, the liquid forced out of the booster spaces enters the push-back spaces and causes a very rapid return stroke from this oint. p While the first part of the return until'the time of unclamping the mold is relatively slow, this is immaterial because at this point the time required for the cooling and hardening of the article in the mold is the limiting factor and there is still ample time for the first part of the retrac tion before the timing motor 92 opens .the

switch 93.

The return of thehead 9 continues until the piswhen there is any possibility of the clamping pressure being released and in fact this IS not.

during the cycle but is at the completion of the cycle during dwell at the uppermost position.

If the switch 86 is locked, the action of the press in returning to the upward position causes opening of limit switch 9|, thus causing repetition of the cycle.

As the head 9 and the platen I4 move downwardly together, no feeding occurs. However, when platen I4 comes to rest by reason of the engagement of the injection nozzle 20 with the mold half 4, continued movement of the head 9 downwardly causes the rack 56 after a predetermined period, depending upon the adjustment of the vertical rod 51, to engage the pinion 53 and cause rotation thereof in a direction clockwise of Fig. 9. This causes feeding by the feed screw 59 into the chamber I9 proportionately to the extent of travel of injection plunger 43 downwardly. 'As the injection plunger is withdrawn, the overrunning clutch embodied in pinion 53 does not feed. As the injection plunger is withdrawn, the accumulated granular material in the chamber I9 falls downwardlyinto the top of the heating chamber.

the rods I29.

mold half I24 is mounted on the bolster I25. The clamping and injecting head I26 carries the plunger I2! and contains the clamping pistons I28 which supportthe upper mold half I24 by The injection cylinder carrying platen I39 is constructed in a manner generally similar to that described above and is suspended in a similar manner from the clamping and injecting head by the rods I3I. The oil heating chamber I32 is mounted on the 'lower plate of the platen I39 on a rearward extension of said plate and oil from tank I32 is circulated around the injection cylinder in a manner similar to that with those described above in connection with the" main form of the invention and shown in Fig. 1 The same reference characters are applied to the hydraulic and electrical circuits in Fig. 14 as in Fig. l1. There are some differences and the mode of operation is somewhat different because in this modification the push-back and the main pressing operation eperate on a common piston, namely piston I35, whereas in the main modification described above, the booster and push-back operate against common pistons while the main pressing takes place on pistons which are used only for this function. The main pressing space I34 is connected by a conduit I38 having a check valve I39 to the tank I40 so as to be able to withdraw liquid freely from the tank during a downstroke caused by the booster.

In the modified form, it is unnecessary to employ the two-way valve III described above because of the different arrangement of the booster,

the main pressing space I34. The single check valve I43 takes the place of the three check valves 31, 46 and 41 of Fig. 11. The conduit "having thecheck valve 39 leads from conduit 36 to' conduit II II and is adapted to be opened by the unloading valve 40 which is adapted to be actuated through the conduit M as before.

The operation of the modification of Fig. '14 will be obvious in view of the foregoing detailed description of the operation of the main embodiment. However, for purposes of completeness, it may be set forth briefly as follows:

With the press idling in the position shown in Fig. 14, the pump 62 is delivering pressure liquid into the conduit 64 whence it passes clamping and injecting head I26. The energiza- 'conduit 38 into the main pressing space I33,

. through valve 66 into conduit I33 leading to the stantly delivered into the clamping space above clamping pistons I28 by way of check valve I 43 and conduit 36.

To start the main ram I33 downwardly, the operator closes switch 86. This energizes solenoids 67 and BI, solenoids BI establishing aholding circuit as before for holding these solenoids energized and also establishing a connection between lines 83 and '83 preparatory for the operation of limit switch 1! by cam I8 carried by the tion of solenoid 6'! causes the shifting of the valve member of valve 65 downwardly, thereby discontinuing the application of pressure to the push-back area Hi. The main ram I33 is now moved downwardly at high speed under the action of the booster I36... When the mold halves are clamped, cam I8 closes limit switch 'I'i, causing energization of solenoids 69 and Ill. Energization of solenoid III causes the timing motors as and 92 to begin rotation and also causes the establishment of a holding circuit for holding solenoids 89 and i0 energized. Energization of solenoid 69 causes the valve member in valve 65 to be shifted upwardly, thereby cutting oil the application of pressure to the booster space I 3? and connecting the booster space freel'y back to the tank by way of conduits I09, I08 and Iifll. At the same time, the valve member in valve 36 causes th application of liquid pressure to the main pressing space I34. This causes the main ram I33 to continue downwardly. However, the clamping of the mold has been efiected and clamping pistons I23 now unbottom, the liquid thereabove being forced through valve to and .93, causing de-energization of solenoids 39 and I0, causing the valve member in valve 66 toresume the position shown in Fig. 14, causing the connection of the main pressing area to the tank I40 and causing the application of liquid pressure to the booster area I3'I which is full because it was connected freely to the tank during the second portion of the down-stroke and during the first portion of the up-stroke. The shifting of-valve 63 also cuts oif the application of liquid pressure to the main pressing Space I34 and consequently the ram I33 moves upwardly (a) with the press idling switch ans closed. This causes the application of pressure to the {booster space, causing fast traverse and closing of the mold halves.

(b) When the mold halves close, the press head actuates limit switch 11. This causes the timing motors to start and also causesapplication of liquid pressure to the main pressing space. The,

main pressing pistons overcome the clamping pistons, causing the liquid squeezed out of the clamping space to enter the main space, causing injection at high speed.

(0) After completion of the injection stroke, the main pressing space is held under pressure until a predetermined time has elapsed, whereupon one of the timing motors (83) causes the application of pressure 'to the push-back space while continuing its application to the main pressing space and to the clamping space (which is under pressure at all times). This causes the first part of retractionwhile holding the mold halves closed, because the clamping area in conto complete its return stroke because the push- 7o back areaexceeds the booster area.

Summary of operation of both embodiments junction with the push-back area exceeds the.

main area. This continues until the clamping pistons bottom.

"(11) The clamping and injecting head stops when the clamping pistons bottom.

(e) After a predetermined time after the stopping of the head, the timing motor 92 causes the connection of the liquid pressure to the booster areas and causes the main areas to be connected to discharge. Since the push-back area is still connected to the liquid pressure, the push-back area overcomes the smaller booster area, the liquid squeezed out of the booster space being forced into the push-back space and causing a rapid .final retraction. This completes the retraction and the cycle.

From the foregoing, it will be seen that the press of the present invention accomplishes the objects set forth at the outset in an efilcient and satisfactory manner. It will be seen that the unique arrangement of opposed pressure areas aids greatly in bringing about these results. It will further be seen. that the individual portions of the forward and return strokes are carried out at extremely high speed 'whereverthis is advantageous. It wi1l be seen, for example, that the provision of a relatively low booster area makes for a fast traverse preparatory to finalclamping of the mold and the injection stroke. 'It. will be as to discharge into the main area makes for an injection stroke at very high speed. It will further be seen that the cooperation'of clamping and push-back areas in overcoming the main area during the first part of the return is advantageous since it allows the injecting head to come to rest by the automatic cutting out of. the clamping areas when the clamping pistons bottom, thus bringing the head to rest because the main area exceeds the push-back area. It is not necessary to have'high speed during the first part of the return stroke because the mold cannot be unclamped until after a relatively long period of time. It will be seenthat the provision for dwell of the injecting head at this point is accomplished in a unique manner by the timing motor 32/ Finally, it will be seen that by having the opposed does not require an expensive accumulator system but allows the use of a single pump of limited output for the carrying out of the injection cycle in a minimum of time.

While'it was not expressly referred to above, it will be understood that the pump 62 is shifted almost to neutral during the dwell at the end of the injection stroke, while the timing motor 89 is holding the clamping and injecting head at dwell, this shift-ing being accomplished automatically by building up of liquid pressure in conduit 64 and the transfer of this pressure through conduit 99 to the servomotor I of the pump 62. Thus the injection plunger is held under the injecting pressure.

Whilethe invention has been described with particular reference to embodiments thereof which have been found to be very satisfactory, it is to be understood that the invention is not limited to these particular embodiments but that various modifications may be made therein to adapt the invention to various conditions and uses and that the invention is to be limited only as defined in the appended claims.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is:

1. Injection molding apparatus comprising a clamping and injecting head, main hydraulic motor means including a stationary cylinder and movable plunger for moving said head in a clamping and injecting stroke, push-back hydraulic motor means operatively connected with I said head for effecting a retraction stroke of said head, clamping and cushioning hydraulic motor means carried by said head and having a cylinder connected to said head, anda piston movable in saidcylinder, a movable mold half connected to the piston of said clamping and cushioning motor means, and booster hydraulic motor means associated with said main hydraulic motor means for traversing said head at high speed during the first portion of said stroke, the effective push-back area of said push-back motor means exceeding the effective area of said booster motor means, the effective advancing area of said main motor. means exceeding the effective advancing area of said clamping and cushioning motor means, the affective advancing area of said clamping and cushioning motor means plus the effective'push-back area of said push-back motor means exceeding the effective advancing area of said main motor means, and the effective advancing area of said main motor means exceeding the effective push-back area of said push-back motor means.

2. Injection molding apparatus comprising a clamping and injecting head, main hydraulic motor means having an advancing area for moving said head in a clamping and injecting stroke, push-back hydraulic motor means associated with said head and having a push-back area for returning .said head, a movable mold half, and clamping and cushioning hydraulic motor means carried by said head and including a movable element connected to said mold half and provided with a fluid operable clamping area for clamping said movable mold half against another mold half, the advancing area of said main motor means exceeding the push-back area of said push-back motor means and also exceeding the clamping area of said clamping and cushioning motor means, and the combined pushback and clamping areas of said push-back motor means and said clamping and cushioning .motor means having an advancing area for moving said head in a clamping and injecting stroke, push-back hydraulic motor means associated with said .head and having a push-back area for returning said head, a movable mold half, clamping and cushioning hydraulic motor means carried by said head and including a movable element connected to said mold half and provided with a fluid operable clamping area for clamping said 'movable mold half against another mold half, said last-named motor means being adapted to normally project said mold half away from said head, the push-back area of said push-back motor means plus the clamping area of said clamping motor means exceeding the advancing area of said main motor means, the advancing area of said main motor means exceeding the push-back area of said push-back means, means for simultaneously applying common hydraulic pressure to all of said motor means for thereby causing said push-back motor means and said clamping motor means to return said head in opposition to said main motor means, means for thereafter rendering ineffective said clamping area for thereby causing said head to stop and for immediately rendering said clamping area effective should said main motor means move said head by overcoming said pushback motor means.

4. Injection molding apparatus comprising a clamping and injecting head, main hydraulic motor means having an advancing area for moving said head in a clamping and injection stroke, booster hydraulic motor means for rapidly traversing said head during the initial portion of said stroke, a movable mold half, clamping and cushioning hydraulic motor means carried by said head and having a clamping area for yieldingly urging said mold half away from said head, the advancing area of said main motor means exceeding the clamping area of said clamping motor means, means for applying a source of hydraulic pressure to said clamping motor means at all times, means for applying said source to said booster motor means to cause rapid traverse of said head and clamping of said mold half, means for thereafter applying said source to said main motor means for causing said main motor means to overcome said clamping motor means and cause an injection stroke, and means for simultaneously allowing discharge from said clamping motor means to said main motor means while maintaining said mold half clamped for thereby obtaining a more rapid travel of said head in said injection stroke.

5. Injection molding apparatus comprising a clamping and injecting head, a movable mold half, clamping and cushioning hydraulic motor means carried by said head for projecting said mold half away from said head, main hydraulic motor means for moving said head in a clamping and injecting stroke, push-back hydraulic motor means for returning said head, booster hydraulic motor means for rapidly traversing said head in the initial portion of said stroke, a source of hydraulic pressure, means for connecting said source to said clamping motor means at all times, means for connecting said source to said booster motor means to initiate said stroke, means for thereafter connecting said source to said main motor means to complete said stroke,

means for thereafter connecting said source to said push-back motor means for thereby causing jection stroke, push-back hydraulic motor means for returning said head, a movable mold half, clamping and cushioning hydraulic motor means carried by said head and having a movable element for projecting said mold half away from said head in the direction of injection stroke, a source of pressure liquid, means for connecting said source to said clamping motor means at all times, means for moving said head to cause clamping, means for thereupon connecting said source to said main motor means to cause said head to execute an injection stroke and to telescope said clamping motor means, means operative after a predetermined time after completion of said stroke for connecting said source to said push-back motor means for causing said pushback and clamping motor means to overcome said main motor means and cause said head to execute a return stroke, stop means carried by said head for stopping the movable element of said head relative to said cylinder, when said mold halves engage each other.

9. An injection molding machine comprising a stationary mold half, a movable mold half operable to engage said stationary mold half, a movable injection plunger, a movable injection cylinder operable for engagement with said movable mold half, fluid operable motor means for sequentially moving said plunger and said cylinder in unison toward said stationary mold half,

and to telescope said plunger into said cylinder responsive to the engagement of said injection cylinder with said movable mold half, a feed hopper carried with said cylinder, a feed screw carried with said cylinder and adapted to deliver granular plastic from said hopper to said cylinder, a pinion rotatably connected with said screw, means for rotating said pinion in response to the telescopingof said plunger into said cylinsaid clamping motor means and for thereby ren dering said clamping motor means further ineffectual in said return for thereby stopping said head in its return stroke, and means operative after a predetermined time after said stopping for disconnecting said source from said main motor means for thereby causing said pushback motor means to complete said return stroke.

7. A'vertical injection molding machine com- I prising aclamping and injecting head, an injection plunger projecting vertically downwardly from said head, means for vertically reciprocating said head, a stationary mold half, a vertical clamping and cushioning cylinder formed in said head, a fluid operable piston reciprocable in said cylinder, a movable mold half movably connected with said piston for cooperation with said stationary mold half, means carried by said head for limiting relative movement between said piston and said head in a direction in which said piston moves downwardly away from said head, an injection cylinder between said head and said mold halves, and lost motion means for connecting said injection cylinder to said head. v

8. An injection molding machine comprising a reciprocable clamping and injecting head,

clamping and cushioning hydraulic motor means carried thereby, and having associated therewith a movable element supporting a first mold half adapted to engagea second mold half, a

movable injection cylinder between said head and said first mold half and adapted to engage the latter, an injection plunger carried. by said head, a feeding screw carried by said cylinder, and means carried by said head for actuating said feeding screw in response to the travel of der, said means including a rack for engagement with said pinion, and means for adjustably carrying said rack with said plunger.

10. Injection molding apparatus comprising a reciprocable injecting head, an injection plunger carried by said head and movable therewith, hydraulic motor means common to both said head and said injection plunger for reciprocating the same in unison, said injecting head comprising a cylinder having reciprocably mounted therein a fluid operable clamping plunger, a movable mold half operatively connected with said clamping plunger and adapted to be clamped thereby against a cooperating mold half, an injection cylinder between-said movable mold halfand said head for receiving said injection plunger, said cylinder being movable with respect to said mold halves and said" injection plunger, and means hydraulically interconnecting said hydraulic motor means and said clamping plunger for causing the latter to assist the injecting movement of said injection plunger subsequently to the clamping together of said mold halves.

11. In a vertical injection molding press, a

press bed adapted 'to support a first mold half, a stationary press head with a press cylinder mounted thereon, a main plunger reciprocable in said press cylinder and having associated therewith fluid operable advancing and retracting means for advancing and retracting said plunger, a clamping cylinder movable by said main plunger so as to move in unison with and in the same direction as said main plunger, a fluid operable clamping plunger reciprocably mounted in said clamping cylinder, a second mold half supported by said clamping plunger and adapted to be clamped thereby against said first mold half in response to relative movement between said clamping cylinder and said clamping plunger, while said mold halves engage eachv other, an injection plunger connected to said main plunger so as to be movable therewith for injecting molding material into said mold halves, and means responsive to a predetermined clamping'pressure on said clamping plunger for conveying said pressure to said advancing means for aiding said main plunger in advancing said injection plunger during its injecting operation.

12. In a vertical injection molding press, a press bed housing a first fluid reservoir and a plurality of main cylinders, each'of said cylinders having reciprocably mounted therein a fluid operable main plunger, a pressure fluid source for supplying pressurefluid to said main cylinders for actuating said main plungers, a movable press head supported by said main plungers and including a second fluid reservoir and a clamping cylinder, said press head being movable toward said press bed, connecting means for hydraulically connecting said fluid reservoirs and said cylinders respectively, a fluid operable clamping plunger. reciprocably mounted in said clamping cylinder a first mold portion supported by said clamping plunger, a second mold portion supported by said press bed for engagement with said first mold portion, an injection plunger supported by said movable head for injecting molding material into said mold portions, and means responsive to a predetermined movement of said head toward said bed for conveying pressure fluid from said fluid source to said main cylinders to thereby cause said main plungers to move said head toward said bed for creating clamping pressure on said clamping plunger to clamp said mold portions together, and for causing said injection plunger to effect an injecting operation. v

13. In a vertical injection molding press, a movable mold portion, a stationary mold portion, fluid operable means for advancing said movable mold portion toward said stationary mold portion, a fluid operable clamping plunger supporting said movable mold portion, fluid operable means for exerting hydraulic clamping pressure on said clamping plunger to clamp said movable mold portion against said stationary mold portion, an injecting plunger movable by said fluid operable means selectively in unison with or relative to said movable mold portion for injecting molding material into said mold portions, and means responsive to the advancement of said injecting plunger by said fluid operable means while said mold portions are clamped together for conveying clamping pressure from said clamping plunger to said fluid operable means to aid the advancing movement thereof.

14. An injection molding machine comprising a clamping and injecting head, a stationary mold half, a movable mold half, an injection plunger carried by said injecting head, hydraulic motor means for selectively moving said head toward by said head and movable selectively in unison with said head or relative thereto, said cylinder being arranged for cooperation with said injection plunger and said movable mold half and being movable relative to both mold halves, and feeding means operable by said head on movement thereof relative to said cylinder for feeding molding material into said injection cylinderin proportion to said movement.

15. In an injection molding machine, a clamping and injecting head, an injection plunger carried thereby, an injection cylinder adapted to receive said plunger, a first mold half, a second mold half adapted to be engaged by said first mold half, clamping and cushioning fluid operable motor means carried by said head and including a clamping cylinder and a clamping piston connected to said first mold half and recipin the advancing operation of said head.

l6. In an injection molding machine, a stationary mold half, a movable mold half for cooperation with said stationary mold half, an injection cylinder for receiving material to be ejected therefrom into said mold halves, a reciprocable injection plunger for ejecting material from said cylinder into said mold halves, said movable mold half being arranged between said injection plunger and said stationary mold half,

or away from said stationary mold half, a mov: I able injection cylinder carried with lost motion a fluid operable clamping cylinder-piston-assemly for clamping said mold halves together, and fluid operable main motor means operatively connected with said clamping cylinder-piston-assembly and operable to actuate said clamping' cylinder-piston-assembly for clamping said mold halves together and subsequently to actuate said injection plunger for ejecting mate- 'rial from said injection cylinder into said mold halves.

WARREN R. 'I'UCICER. 

